From patchwork Mon Apr 1 17:00:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paulo Alcantara X-Patchwork-Id: 13612881 Received: from mx.manguebit.com (mx.manguebit.com [167.235.159.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 14156BA3F for ; Mon, 1 Apr 2024 17:01:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=167.235.159.17 ARC-Seal: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711990869; cv=pass; b=FuY9Bdb9N5EQlFcZQpx88K8xEhZ8Bq/URcy/mG/pLrMzo5kGQZV8HYEXRpyThdLVHsB7pCm6dOtJbl6PI4fg9YDexvmGElUiIMrGYd7NAy0BY34CsyTr9Lv5BpJGdP5aFmAq0mwqkMS/9h0ALGBK1m8/hJ8Mcyt9e3saITsfucE= ARC-Message-Signature: i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711990869; c=relaxed/simple; bh=Hm4pe1dtcqy+XkJpKE5NwR9CXqv0nOJ6yCa9c820iZ0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=bwyvDkwbWhHhCMs4rvy6qkDHTnCPUNz9pO7Bmm3MMS4/3oFix3cdGZAKDMCtYxJxbmuwGCYTiV9pbb7nQmJIaOgZJzyyBavsCvMcf+16lJg85t2TGT7ekBLj4vzsV54JThIx2yz3uVHBMA039V1kQ90jhsKCysNA6uA/+IBbBVQ= ARC-Authentication-Results: i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manguebit.com; spf=pass smtp.mailfrom=manguebit.com; dkim=pass (2048-bit key) header.d=manguebit.com header.i=@manguebit.com header.b=FrAkolNK; arc=pass smtp.client-ip=167.235.159.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=manguebit.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=manguebit.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=manguebit.com header.i=@manguebit.com header.b="FrAkolNK" From: Paulo Alcantara DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=manguebit.com; s=dkim; t=1711990859; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=LM2tp5wQzMV7jvCbCZhAyg+TifhkXqveyzripZjJMwc=; b=FrAkolNKSlXhDDh86sVyU5pU+v3cgiaVsZ98MmcWuiaJAILmd81XTw/KU2ylvl0Uk2ckIv 0FskqV9L8tUCZv7j6ywfG2EWhUEJLxeKHP20r+juLeMNtr4EqBQtMBEJ+3s8Z9ixRXVupx cbR7paTLkMvx4fJ96+egNrEX/yRKkGWFEhyeLX14UmLww6ZETcbrKgLLqPuiCfSLsbV0jg euFlR9BUU72/3SSCykEBwZe1/5ka7GCaIVTursP174L4VmC+b5qaEZuWbEsbPil020919k +A967U8i8tMA563Gf8QzTqA8JmsDEw1dMPGPvLsoV3SO2wJ7Go3VvFhAhhIApw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=manguebit.com; s=dkim; t=1711990859; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references; bh=LM2tp5wQzMV7jvCbCZhAyg+TifhkXqveyzripZjJMwc=; b=bQIL5roxyvezMaF7ObKetr1sEkVLnL+zRhFwGeGsxrYlLfYz/PE0YKl9qOBYlbVOzvg6lt 84ko9pNHHWHu4chaPnhlI5yEsmmgEk41+hnpeU7OdqCM1e6gqWk3ULbe7WksDSPStne4Ke pALyCNYPkwRKNxjdHM+JjV6JqWYBIHe3cbxvoVyl1w8kdzum0qrp8GklhUxVFWjeY/o7AB sX3a4vpUIJWdFvVCSHD2dO32mGXpnJWUcVJSJmDl9qZkIzcolus7JbezQMiqOTomExRyVg xYb39s6HACpomQhIOXYcWNeuWM5F9Omj+rdNWkNZyBWpjOBQ/qJNUMzJYEYzEQ== ARC-Authentication-Results: i=1; ORIGINATING; auth=pass smtp.mailfrom=pc@manguebit.com ARC-Seal: i=1; s=dkim; d=manguebit.com; t=1711990859; a=rsa-sha256; cv=none; b=LcOaD4xO0DMu6rUH13OkDKgDDZcx1TRgBF9KDyFY1LoXuPnSV8XVs+tH8q2MagAzTRPbhQ oSDfIOluKMF/L+2lypi9ZC697lLtWeMJCiN0AkmlrtqHLcGIpowisdTE3wDeCikfkYI0Fs 7fcOMu0TuEzs1k+tVEqSy8H7YK+N+vtYaqoyzqHlkAX/zfLHN4t41xvmFDi8BzYuET7e9S Z3jLljCRW8GVe3MacB6PJlsLUk6efns/eFiEZmV7K4TT5VT8D6w+oxX28MYcteaKKKA6Ta CbFYAT50KBp4CHHiJyAKS17srJmoB9/9N3PeS5mIuWQkXOn9p5rIYNczrYloJg== To: smfrench@gmail.com Cc: linux-cifs@vger.kernel.org, Paulo Alcantara Subject: [PATCH] smb: client: fix UAF in smb2_reconnect_server() Date: Mon, 1 Apr 2024 14:00:44 -0300 Message-ID: <20240401170044.86991-1-pc@manguebit.com> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The UAF bug is due to smb2_reconnect_server() accessing a session that is already being teared down by another thread that is executing __cifs_put_smb_ses(). This can happen when (a) the client has connection to the server but no session or (b) another thread ends up setting @ses->ses_status again to something different than SES_EXITING. To fix this, we need to make sure to unconditionally set @ses->ses_status to SES_EXITING and prevent any other threads from setting a new status while we're still tearing it down. The following can be reproduced by adding some delay to right after the ipc is freed in __cifs_put_smb_ses() - which will give smb2_reconnect_server() worker a chance to run and then accessing @ses->ipc: kinit ... mount.cifs //srv/share /mnt/1 -o sec=krb5,nohandlecache,echo_interval=10 ls /mnt/1 &>/dev/null sleep 30 kdestroy sleep 10 umount /mnt/1 ... CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \\srv Send error in SessSetup = -126 CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed CIFS: VFS: \\srv Send error in SessSetup = -126 general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc2 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/2014 Workqueue: cifsiod smb2_reconnect_server [cifs] RIP: 0010:__list_del_entry_valid_or_report+0x33/0xf0 Code: 4f 08 48 85 d2 74 42 48 85 c9 74 59 48 b8 00 01 00 00 00 00 ad de 48 39 c2 74 61 48 b8 22 01 00 00 00 00 74 69 <48> 8b 01 48 39 f8 75 7b 48 8b 72 08 48 39 c6 0f 85 88 00 00 00 b8 RSP: 0018:ffffc900001bfd70 EFLAGS: 00010a83 RAX: dead000000000122 RBX: ffff88810da53838 RCX: 6b6b6b6b6b6b6b6b RDX: 6b6b6b6b6b6b6b6b RSI: ffffffffc02f6878 RDI: ffff88810da53800 RBP: ffff88810da53800 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: ffff88810c064000 R13: 0000000000000001 R14: ffff88810c064000 R15: ffff8881039cc000 FS: 0000000000000000(0000) GS:ffff888157c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe3728b1000 CR3: 000000010caa4000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: ? die_addr+0x36/0x90 ? exc_general_protection+0x1c1/0x3f0 ? asm_exc_general_protection+0x26/0x30 ? __list_del_entry_valid_or_report+0x33/0xf0 __cifs_put_smb_ses+0x1ae/0x500 [cifs] smb2_reconnect_server+0x4ed/0x710 [cifs] process_one_work+0x205/0x6b0 worker_thread+0x191/0x360 ? __pfx_worker_thread+0x10/0x10 kthread+0xe2/0x110 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x34/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Signed-off-by: Paulo Alcantara (Red Hat) --- fs/smb/client/connect.c | 87 +++++++++++++++++------------------------ 1 file changed, 36 insertions(+), 51 deletions(-) diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c index 9b85b5341822..ee29bc57300c 100644 --- a/fs/smb/client/connect.c +++ b/fs/smb/client/connect.c @@ -232,7 +232,13 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server, spin_lock(&cifs_tcp_ses_lock); list_for_each_entry_safe(ses, nses, &pserver->smb_ses_list, smb_ses_list) { - /* check if iface is still active */ + spin_lock(&ses->ses_lock); + if (ses->ses_status == SES_EXITING) { + spin_unlock(&ses->ses_lock); + continue; + } + spin_unlock(&ses->ses_lock); + spin_lock(&ses->chan_lock); if (cifs_ses_get_chan_index(ses, server) == CIFS_INVAL_CHAN_INDEX) { @@ -1963,31 +1969,6 @@ cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx) return rc; } -/** - * cifs_free_ipc - helper to release the session IPC tcon - * @ses: smb session to unmount the IPC from - * - * Needs to be called everytime a session is destroyed. - * - * On session close, the IPC is closed and the server must release all tcons of the session. - * No need to send a tree disconnect here. - * - * Besides, it will make the server to not close durable and resilient files on session close, as - * specified in MS-SMB2 3.3.5.6 Receiving an SMB2 LOGOFF Request. - */ -static int -cifs_free_ipc(struct cifs_ses *ses) -{ - struct cifs_tcon *tcon = ses->tcon_ipc; - - if (tcon == NULL) - return 0; - - tconInfoFree(tcon); - ses->tcon_ipc = NULL; - return 0; -} - static struct cifs_ses * cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx) { @@ -2019,48 +2000,52 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx) void __cifs_put_smb_ses(struct cifs_ses *ses) { struct TCP_Server_Info *server = ses->server; + struct cifs_tcon *tcon; unsigned int xid; size_t i; + bool do_logoff; int rc; - spin_lock(&ses->ses_lock); - if (ses->ses_status == SES_EXITING) { - spin_unlock(&ses->ses_lock); - return; - } - spin_unlock(&ses->ses_lock); - - cifs_dbg(FYI, "%s: ses_count=%d\n", __func__, ses->ses_count); - cifs_dbg(FYI, - "%s: ses ipc: %s\n", __func__, ses->tcon_ipc ? ses->tcon_ipc->tree_name : "NONE"); - spin_lock(&cifs_tcp_ses_lock); - if (--ses->ses_count > 0) { + spin_lock(&ses->ses_lock); + cifs_dbg(FYI, "%s: id=0x%llx ses_count=%d ses_status=%u ipc=%s\n", + __func__, ses->Suid, ses->ses_count, ses->ses_status, + ses->tcon_ipc ? ses->tcon_ipc->tree_name : "none"); + if (ses->ses_status == SES_EXITING || --ses->ses_count > 0) { + spin_unlock(&ses->ses_lock); spin_unlock(&cifs_tcp_ses_lock); return; } - spin_lock(&ses->ses_lock); - if (ses->ses_status == SES_GOOD) - ses->ses_status = SES_EXITING; - spin_unlock(&ses->ses_lock); - spin_unlock(&cifs_tcp_ses_lock); - /* ses_count can never go negative */ WARN_ON(ses->ses_count < 0); - spin_lock(&ses->ses_lock); - if (ses->ses_status == SES_EXITING && server->ops->logoff) { - spin_unlock(&ses->ses_lock); - cifs_free_ipc(ses); + spin_lock(&ses->chan_lock); + cifs_chan_clear_need_reconnect(ses, server); + spin_unlock(&ses->chan_lock); + + do_logoff = ses->ses_status == SES_GOOD && server->ops->logoff; + ses->ses_status = SES_EXITING; + tcon = ses->tcon_ipc; + ses->tcon_ipc = NULL; + spin_unlock(&ses->ses_lock); + spin_unlock(&cifs_tcp_ses_lock); + + /* + * On session close, the IPC is closed and the server must release all + * tcons of the session. No need to send a tree disconnect here. + * + * Besides, it will make the server to not close durable and resilient + * files on session close, as specified in MS-SMB2 3.3.5.6 Receiving an + * SMB2 LOGOFF Request. + */ + tconInfoFree(tcon); + if (do_logoff) { xid = get_xid(); rc = server->ops->logoff(xid, ses); if (rc) cifs_server_dbg(VFS, "%s: Session Logoff failure rc=%d\n", __func__, rc); _free_xid(xid); - } else { - spin_unlock(&ses->ses_lock); - cifs_free_ipc(ses); } spin_lock(&cifs_tcp_ses_lock);